Signors of one-thibd to lawrence f



Dec. 22, 1931. THOMAS ET AL 1,837,598 FLUID PRESSURE DEVICE Filed March 18, 1950 W X? ai g 8 (8 x 10 T 10 A i 11 11 75 Sburce of FZuidPmssure Patented Dec. 22, 1931 i A, UNITED {ST-A Application fiiea'iuarcii 18, 1930.

We will describe two'forms of fluid pres-c sure devices embodying our invention, and will then'point out the novel features thereof in claims.

' In the accompanying drawings, Fig. is a sectional view, partly diagrammatic, showing one form of fluid pressure'device embodying our invention. Figs, 2 and 3 are views show ing modified forms of fluid pressure devices also" embodying our invention.

1 Similar reference characters refer tosimi lar parts in each of the several views. 7 i

' Referring first to Fig. 1, the reference character 1 designates a cylinder upon one end of operated signal, here which is screwed a cap 2. Threaded into the cap 2 is a source of fluid drawings), the condition of which the device embodying our invention is intended to indicate. For example, the pipe 3 may be connected with the main reservoir of the usual and well known air I customarily employed on street railway cars and the like. Into the other end of cylinder'lc is threaded a cylinder head 4, which is provided with openings 5 communicating with theinterior; of a conical cover 6 attached to the head 4. The cover 6 is open at its upper end, and'is provided with-a fluid pressure I shown as a whistle 7, arranged to be operated by fluid pressure admitted tolth'e cover through the openings 5, in'head. 1

Reciprocable within the cylinder 1 is a piston 8, which is biased downwardly bysuitable means, here shown as a helicalspring 9 having one end attached to the piston and the other end attached to the inner surface of thehead4. V V t p A pipe 11 is connected atone end with the source of fluid pressure through pipe 3' and terminates at its other end in a port 10 in the wall of cylinder 1. The pipe 11 contains a manually operable valve 12, by means of which the pipe may at times be closed for a FLUID-PRESSURE DEVICE i the'piston occupies pipe 3 which communicates with pressure '(not shown in the brake system, such as is fluidpressure on opposite sides of 8 is now substantially equahit follows that i PITTSBURGH, PENNSYL- Serial t 436,821

purpose which will be described he'reinaftert proportioned "that under 1 The parts are so normal conditions, that 1s, when the pressure of the source to which pipef3 isconnected is above a predetermined Value, the force exerted on the lower s1de of piston 8 18- greater than the forceexerted by spring 9 solthat the position in which it is illustrated in full lines in the drawings. It,

will be noted that whenthe piston occupies th s position, it is above the port 10 by means of which pipe 11 is connected with the cylii1- der, so that the supply of'fluid pressure to thecover 6 through openings 5 is interrupted and the whistle 7 is not operated, If, however, the pressure supplied low a predetermined valu the force exerted by spring 9 moves the piston 8 downwardly against theforce exerted by fluid} pressure on the underside of this piston, This movement of the piston uncovers port 10 and :11:

lows fiuidjpressure to flowthrough pipe 11 to the upper end of the cylinder 1 above piston 8. The fluid pressure thus supplied to the upper endof the cylinder passes through the openings 5 into the cover 6' and operates the whistle to thepres'sure' in'pipe 3 has fallen below the predetermined value for which the device is intended to operate. Furthermore,'the'pressure supplied to'the upper. sideof piston 8' through port 10 assists the spring 9 injnioving the piston downwardly sothat the piston,

moves smartly to its lower position indicated bybroken' lines in the. drawings. Since the the piston the piston will remain in its lower p osition due to the bias of spring 9, and that the whistle 7 willcontinue to operate,"even though the pressure in pipe 3 is again restored above its predetermined value. In order to restore the device to its normal position, the valve 12 may be operated to close pipe 11. If the pressure in'pipe3 is now above the predetermined value, piston 8 will be moved upwardly to its full line position, thereby disconnecting port 10 from the upper end of the cylin der and discontinuing the operationof whistle 7. The valve 12 may now be reopened,

give a positive indication that i or 'rrrjrsnunsri, PENNSYLVANIA, As-

and the device will subsequently indicate a decrease in pressure as described .Vabove; r

In the mod fication shown 1n Fig. 2, the

' tegral with the cylinder l this-construction is that 7 been actuated a decrease in fluid pressure,

ifj'the' pressureis again restored tola' sufli- 1 we "claiimis ation, of the pipe 11 is replaced by nects the p'ort lOwith a port a pipe-11 which con- 1,4 in cylinder 1 at a PQlnt below thc lowestposition of the piston 8. The pipe 11 .be made in- 1 and contains a restricted orifice 13. \Vith theapparatus c'on-.

structed 'ashere' ShOVVlL E decrease in the pressure supplied to pipe mined value allows the downwardly in the same manner as described in connection with Fig. 1." WVhen-the'pismn occupies lower position, however, fluid pas ng through pipe l1v operates the whistle T,'Ibut due to the restricted orifice 13, there is a considerable difiere'nc'e in 'pressure onthe two sides fo'fthe'pisto'n 8.

after the device has ci'ently highvalue, thepisto n 18 will be auto matically" restored to its, upper thereby discontinuing the operation of the whistle and restoring the device to its normal condition.

As, shownin Fig. 3,the inner =wall of the cvlincler'l is provided with a flutefor groove piston '8 when the piston is in its lower position. WVhieii the piston is held in its upper position, however, the groove is blanke-diand no fluid issupplied'to'fthe upper end or" the cylinder for operating whistle 7, The

groove 11 is preferablyproportioned in suchmanner that the flowof fluid pressure there through, while sufiicient tooperate the wliis-' 'tle 7', allows the pistonto be restoredauto store the piston.

ltshould be pointed out that the devices here disclosed may be adjustedlto operate at any desired pressure by properly proportion] ing the variouspart's, Furthermore, by employing springs 9 oii'diff'erent strengths, the same device may be adjusted to operate at different pressures. 7 V

Ase ndicated above, devices embodying our invention are particularly suitable for use in connection with the air brake system of street railway cars; Infthese systems the .pressure'available in the inn-in reservoir is operate to I gauge,

be pointed 3 below apredeter-- piston 8 to move One advantage of spir t position, 7

m an Port n 7 c 7 djer for supplying flu d pressure to said" si'gnalj source falls below shown in 1', 2 and 3 is iden; ticalrin' movlngthe piston from its normal or to connect said portwith usually indicated by means of the customary but by the addition of a deviceem bodying our invention, a positive audible in dication is givento call theattention of the operatorto the condition of the equipment at a critical time, that is, at the instant that the pressure falls below a safe value, I

devices embod ing our invention are particularly suitable or use in connec't1on with trackwayair brake systems, it should out that they are'not liinited to such use but are equally applicablewhere'ver tit isfi'de'sired' to give a positive indication when the-pressure ofa'source falls below a definite predetermined value.

' A Although we have herein shown and, de scribed only two forms offluidjpressure de; vicesfembody-in'g our inventio" t' i'sfu er-j st d a i u ng sand me ficatm I may be made therein within the scope. ofthe appended claims without depar. tronithe and'scopeof our invent n.

hi sid ie ir li m nt 1 H v ng 1. In combination witha source of; fluid pressure," a cylinder containinga pistonbia sed t0 6 .PQ-Sitionbufi no mal y hel i fiq l efl position by pressure from said "source sig} theside wall-ofsaicl cylin;

if and only if said jPIS tQII H IOV B S. away from saidothe'r position. j

2. In combination with i a pressure,

a "cylinder containing a; piston,

c means for connectin said source'with said cylinder to move sa d p ston to one position, v

biasing ine'ans for movingflsaid piston away from said'onfe position if the pressure ofs icl p min d value; a, signal, anda port in the side wall of said'cyl ilid'er for connectinglsaid signal; with: said source i'vhe'n said pistonis movedfawa ffroml 3. V In 'co'mbinjati with a source: o filuid,

Pr s u & y nder h viil' on n i ne t ed with saidsource, a signal connected with the otherend of the cylin'derfa onefend oominunicatingfw th saic one nd the cylinder and having the other end terx n natingfina port mire wa of Sai ylind and alpisi on in Said; cylinder biaSd ltOWaIld said onee ndv of said cylinderandoperatinq h l one end or tl' of said cylinder pending upon the; p res' sure of said source; I" i "4. In combination with a sourceof P es a y e hav g ne end conned; d with s id so rc a; ignal con e ted-wi h the other endof the cylinder, a pipe having o en mmlln ce nsw th a t 'y ln edlhav 'ngi he: o her eni terminatingin a port in thefwall of said cylinder, an a pi t n n Sa y d r, ias d "towa d. said e n 1;0i, said cylinder and'qp rf uhg Q a no w h sa d ot e p fei in: a in inder when the termined value. 5 In combination with a source of fluid v having a groove which the cylinder when the pressure of saidsource is below a predetermined value but to connect the port with said oneend of the cylpressure is above such predepressure, a cylinder having one'end connected with said source, a signal connected with the other end of the cylinder, a pipe having one end communicating with said one end of the cylinder and having the otherend terminating in a port in the wall of said cylinder, a piston in said cylinder biased toward said one end of said. cylinder and'operating to connect said port with one'end or the other of said cylinder depending upon the pressure of said-source, and. a manually operable valve 1n said pipe.

6. In combination with a source of fluid 'i pressure, a cylinder having one end connect ed with said source, a signal connected with the other end of the cylinder, a plpe contain; mg a restricted orlfice and having one end communicating with said in a port in the wall of said cylinder, and a piston in said cylinder biased toward said one end of said cylinder but operating to connect said port with said other end of said cylinder only when the pressure of said source falls below a predetermined value.

7. In combination with a sourceof fluid pressure, a cylinder having one end connected with said source, a signal connected with the other end of the cylinder, a piston biased toward said one end of the cylinder but normally urged to the other end of the cylinder by pressure from said source, said cylinder fluid past said pistonwhen the piston is ad- Jacent said one end of the cylinder.

8. In combination with a source of fluid pressure, a cylinder having one end connect ed with said source, a signal connected with the other end of the cylinder, a piston in said cylinder normally held in one position by fluid pressure in said one end of the cylinder, biasing means constantly urging said piston against the force applied by fluid pres sure in such one position to move the piston away from-said one positlon if the pressure of said source falls below a predetermined means operating 1f Sitld piston value, and

moves away from said one position to supply fluid pressure to said other end of the cyl--' inder to operate said signal and to equalize pressureon opposite sides of said plston.

In testimony whereof we afiix our. signa 1 tures. V

' JOSEPH THOMAS.

ANTHONY J. FLANIGAN.

one end of the cylis inder and having the other end terminating allows the flow of 

